Spark-plug



N. ALEXANDER.

SPARK PLUG.

APPLICATION FILED AUG.24, ism.

Patented Aug. 12, 1919.

BEST AVAILABLE Corr UNITED STATES PATENT OFFICE.

ALBERT NELSON ALEXANDER, OF BERGENFIELD, NEW JERSEY,

SPARK-PLUG.

Specification of Letters Patent.

Patented Aug. 12, 1919.

Application filed August 24, 1917. Serial No. 188.005.

To all whom. it may concern:

Be it known that I, ALBERT N. ALEXANDER,

' used insuch adevice.

packing or insulation for spark plugs, yet

I have devised a special form of core as will Among the objects-of the int-'entionytherefore, is to provide a spark plug from which porcelain or the like is eliminated and for which I substitutea core of mica or its, equivalent. lVhile I am aware that it is not broadly new with me to employ mica as a be set forth more fully hereinaften Another object of the invention is to provide a novel type of adjustable ignition con- 'ilZlCl'. member in the nature of a thnnble screw threaded into the inner end of the body of the plug and having at its inner end a central hole surrounded by a non-corrodible sleeve and having at its inner end a circular series of deep notches with which cooperates a locking member held in place by the body of the engine into whichthe plug is fitted. V

lVith the foregoing and other objects in view the invention consists in the arrangement and combination of parts hereinafter described and claimed, and while the invention is not restricted to the exact detailsof construction disclosed or suggested herein, stil for the purpose of illustrating a practical embodiment thereof reference is had to the accompanying drawings, in which like reference characters designate the same parts in the several views, and in which-- Figure 1 is a vertical central sectional view of my improvementin operative position.

Fig. 2 is a transverse sectional detail on the line 2--2 of Fig. l.

Fig. 23 is a similar view on the line 33. Fig. i is a plan view of the contact thimble sluuving especially the notches; and

Fig. 5 is a detail perspective view of a washer used in the outer end portion of the device.

Referring now more particularly to the drawn'igs 1 show a spark plug comprising a metal body 10 screw threaded at 11 for cobperation with the engine body- 1221s usual.

This body 10 as heretofore ishollow and zulaptedto carry within the central portion thereof and spaced from the middle of the body a contact pin 13 having at its innerend a contact point 1-1 and having its outer end screw threaded'for the accommodation of lock washers 15 and 1G, and binding nut 17 One branch of the electric-circuit," not shown, is adapted to be connectedeither between the'nut 17 and the washer 15 or snapped directly upon the nut ,17 in the grooie 17 thereof.

Tapped into the inner end of the plug body 10 is a contact thimble 18 having a -peripheral flange 19 provided with a series of equally spaced notches 90, and provided with a hub 21 having direct cooperation with the threaded end of the plug 10. The upper or inner edge of the hub 21-.is pro-.

vided with a series of equally spaced notches 22, one for each'notch 20 and in the same radial plane thereof. See Fig. 1. .I show by way of example a construction in which I employ five of these notches 22 and I suggest that the threads connecting the thimble with the plug body 10 be made twenty per inch. I

23 indicates a locking member shown as a screw tapped through the externally threaded portion 11 of the plug-10, the axis of the screw being arranged at an angle of about thirty degrees to the axisof the contact. pin 13. The inner end or-point of the screw 23 is adapted to be located in any one of the notches 22 While the outer or head end of the screw lies within the threaded surface.

at'll and embraced byv the body 12 of the engine when in operative position. The contact sleeve 2-tcarried in the center of the inner end of the thimble constitutes the contact member coiiperating with the contactpoint 14.v This sleeve ismade preterably of nickel or some sin'iilar non-corrodible material and is adjustable toward or from the contact point 14 by movement of .the thimble up or down with respect to the body 10, the adjustment being made secure by means of the screw 23. If the threads of-the thimble be twenty per inch and there be employed five of the notches 22, it follows that the design provides for an adjustment of the contact thimble in hundredths of an. inch.

This adjustment is effected when the plug 10 is removed from the engine body so that the screw 23 may be withdrawn from the notches 22. The notches 20, however, formed in the periphery of the flange l9 serve not only as a means for facilitating the rotation of. the thimble, but as indicating means to show the operator when a notch 22 registers with the screw, this indication being efiective by alining a notch with the outer end of the screw.

In place of the porcelain core that is com monly used in spark plugs and which is so apt to become broken or cracked and hence render the spark plug useless, especially in high powered engines such as are used in aeroplanes, I employ a core the main portion of which consists of a roll or rolls of 'mica 25. The contact pin 13 is provided at about its central portion within and spaced from theiniddle of the body'lO with an enlargement 13' in the nature of a frustum of a cone, but with convex sides, The inner surface of the body 10 opposite and spaced from this concial enlargement is of practically'the same formor parallel to said enlargement. The upper end of the body 10 is recessed at 26 or surrounded by a smallupstanding flange 27, the flange being remote from the inner surface of the body 10 whereby the recessed rtion 26 constitutes a seat or shoulder. rollof micax25 enibraces all of the enlargement13' and extends both above'and below the same and ,is so designed as to snugly fill the space between the enlargement and the inner wall of the body. Below the enlargement, however, there are provideda pair'of spaces 28 and 29. The space 28 immediately surrounds the inner end of the contact pin while the other space 29 lies between the relief mica 25 and the body '10 of the plug. The contact pin therefore is well spaced and insulated from the metal body10."

30 indicates a mass of mica in the nature of flat disks or washers surrounding the outer cylindrical end portion'of the core 25 and the contact pin .13; The lower or inner end washers 30 are seated in the recess 26 and within the flange 27 and all of these washers 30 are fitted closely upon the roll of mica 25. The disks'or Washers of mica are coextensive, as a mass, with the outer end of the core and against the outer element of the same is located the lock washer 15. The inner lock washer 16 is fitted upon the threaded end of the contact pin and lies against the upper. or outer end of the core and within a recess in the inner or lower assist in olding the same in position when spark plug. If desired the outer surface oi the enlargement 13 may be rough or knurled at 13 to increase the grip upon the mica.

A spark plug made in accordance with this invention is-absolutcly leak proof and heat resisting and consequently it cannot be short circuited by oil or grease. which is so likely to accumulate in the crack of a. split or broken porcelain core. Further more the core is automatically self cleaning with respect to soot and carbon and can easily be adjusted as to the spark gap to accommodate it to any magneto which may be employed to generate the ignition spark. Again, the mica core is of such a nature that it cannot be destroyed either by heat or the explosion within a cylinder. I claim:

'1. A spark plug, comprising a hollow metal body having a portion of its inner surface tapered and having at its outer end an annular recess, a roll of mica fitted within the tapered portion of the body and extending beyond the outer end of the body, a series of flat mica washers surrounding said extending end of the roll of-mica and seated in said recess, a contact pin projecting through the mica core and having a tapered enlargement fitted within the said core, means coiiperating with the outer end oi the contact pin and bearing against the outer end of the series of mica washers to hold the parts all in firmly united condition. and a thimble screwing in the outer end of the body and provided with a contact sleeve.

2. A spark plug, chm rising a hollow body having a portion-"o its inner surface tapered and having at its outer endan annular recess, a roll of mica in the y and projectingbeyond the outer end ofarhe body, aseries of flat mica washers surrounding the projecting end of the mica roll, the inner washers being seated in the recess oi the ALBERT NELSON ALEXANiDER. 

